As more data is becoming available on the Internet, providing secure access to data is becoming more difficult. Blogging services such as LiveJournal, attempt to provide some security. Most such services enable you to set the security level of entries when they are posted or edited. Generally speaking, the security levels include public access, access by named friends or friend groups, and custom access. This type of security is enforced by using cookies stored in a visitor's web browser to track who is logged in and show only those entries that the visitor is authorized to see. This creates a “walled garden” method of security. However, it is impossible to create such security for a blog (web log) which permits RSS (Really Simple Syndication) or other syndication, short of using “all or nothing” methods such as .htaccess. Once content is released onto the Internet, it is generally considered insecure by its nature.
Atom is an XML-based document format and HTTP-based protocol designed for the syndication of Web content such as web logs and news headlines to Web sites as well as directly to user agents. Atom defines a framework for encryption, following the XML Encryption Syntax and Processing W3C Recommendation 10 Dec. 2002, described at <http://www.w3.org/TR/xmlenc-core/>
Generally speaking, handling the decryption key is the most difficult part. There are two options: (secret) key exchange or using public key encryption. The content creator and content consumer can exchange symmetric keys, using various configurations. For example, a masked key may be included in the content. Alternatively, the creator can encrypt the content with the consumer's public key, ensuring that only the consumer (possessor of the private key) can decrypt it. However, both of these options suffer from the flaw that they require individual set-up for the encryption for each recipient. This makes the encryption option cumbersome.